Analysis of the riparian flora of the river Ilse (Harz mountains and northern foreland, Germany) with special regard to nitrophytes and alien plants

345 cormophyte species have been identified along the banks of the river Ilse (length some 42 km) by random sampling on 45 plots. Further mapping increased the number of riparian species to 391 species living on an area of 42 ha along the river banks. This shows the suprisingly high cormophyte diversity of the banks of small rivers. The investigation is a basis for a longtime monitoring of the riparian flora. By use of the riparian flora it is possible to classify the course of the river Ilse into different parts characterised by index species. It is shown that river banks are important places for neophytes. Their amount within the border vegetation depends on the morphology of the banks und the distance to settlements. Gardens play the most important part as source of the neophytes